英文:
Go panics on when having functions declared in code but not called
问题
上下文中的代码段是关于在尝试设置gorm时转换标准的revel/gorp示例的一部分。
然而，即使定义了Begin()、Commit()、Rollback()方法，也足以导致Go进入panic状态。
将方法定义注释掉可以阻止panic。我似乎无法理解为什么不调用这些方法（注意revel.InterceptMethod调用已被注释掉）会导致panic发生:/
英文:
Context:
https://github.com/fusspawn/tserver/blob/master/app/controllers/gorp.go
As part of trying to get gorm setup I tried to convert the standard revel/gorp examples.
However. even having the Begin(),Commit(),Rollback() methods defined is enough to cause go to panic.
TRACE 2015/09/06 17:37:47 harness.go:126: Rebuild
INFO 2015/09/06 17:37:47 build.go:172: Cleaning dir tmp
INFO 2015/09/06 17:37:47 build.go:172: Cleaning dir routes
INFO 2015/09/06 17:37:47 build.go:172: Cleaning dir tmp
INFO 2015/09/06 17:37:47 build.go:172: Cleaning dir routes
TRACE 2015/09/06 17:37:47 build.go:151: Exec: [/usr/bin/git --git- dir=/home/fusspawn/go/src/github.com/fusspawn/tserver/.git describe --always -- dirty]
TRACE 2015/09/06 17:37:47 build.go:94: Exec: [/usr/bin/go build -ldflags -X github.com/fusspawn/tserver/app.APP_VERSION "git-2588ef1" -tags -o /ho
me/fusspawn/go/bin/revel.d/github.com/fusspawn/tserver/tserver github.com/fusspawn/tserver/app/tmp]
TRACE 2015/09/06 17:39:14 app.go:56: Exec app: /home/fusspawn/go/bin/revel.d/github.com/fusspawn/tserver/tserver [/home/fusspawn/go/bin/revel.d/git
hub.com/fusspawn/tserver/tserver -port=46276 - importPath=github.com/fusspawn/tserver -runMode=dev]
INFO 2015/09/06 17:39:14 revel.go:329: Loaded module static
INFO 2015/09/06 17:39:14 revel.go:329: Loaded module testrunner
INFO 2015/09/06 17:39:14 revel.go:206: Initialized Revel v0.12.0 (2015-03-25) for >= go1.3
INFO 2015/09/06 17:39:14 main.go:30: Running revel server
TRACE 2015/09/06 17:39:14 controller.go:402: Registered controller: App
panic: reflect: call of reflect.Value.Type on zero Value
goroutine 1 [running]:
runtime.panic(0x88cec0, 0xc21011b7a0)
/usr/lib/go/src/pkg/runtime/panic.c:266 +0xb6
reflect.Value.Type(0x0, 0x0, 0x0, 0x0, 0x0)
/usr/lib/go/src/pkg/reflect/value.go:1698 +0x79
github.com/revel/revel.findControllers(0x7f365698bea8, 0x9186e0, 0x0, 0x0, 0x0)
/home/fusspawn/go/src/github.com/revel/revel/controller.go:321 +0x25a
github.com/revel/revel.RegisterController(0x9172a0, 0x0, 0xc2100c4bf0, 0x2, 0x2)
/home/fusspawn/go/src/github.com/revel/revel/controller.go:400 +0x1f3
main.main()
/home/fusspawn/go/src/github.com/fusspawn/tserver/app/tmp/main.go:150 +0x141b
TRACE 2015/09/06 17:39:14 controller.go:402: Registered controller: GormController
TRACE 2015/09/06 17:39:14 controller.go:402: Registered controller: Static
TRACE 2015/09/06 17:39:14 controller.go:402: Registered controller: TestRunner
Commenting out the method definitions will stop the panic. I cant seem to understand how not calling these methods (note the revel.InterceptMethod calls are commented out) can make the panic happen :/
答案1
得分: 2
根据 Revel 文档，系统在调试模式下通过扫描源代码目录中的内容来查找控制器。你看到的错误是由于 Revel 在进行控制器扫描初始化期间进行动态反射时出现问题。现在的问题是：为什么它在扫描控制器时出现问题？
你的代码似乎试图在 EventStream 中扩展一个控制器，而 Revel 调试控制器发现代码将尝试将其读取为一个控制器。然而，目前的代码违反了框架的预期，它嵌入了一个 *GormController 而不是 GormController，请参考控制器文档的最后部分。
我认为控制器发现逻辑只是因为这个问题而出错了。修复 EventStream 结构定义。
如果这样修复了你的问题，你可能应该向 Revel 的开发人员发送一个错误报告，因为你收到的错误消息非常糟糕且不具有局部性，因为它在失败时没有提到它试图注册为控制器的名称。
英文:
According to the Revel docs, the system looks for Controllers in debug mode by scanning your source directory for anything that does an anonymous embedding of a *Revel.Controller. The error your're seeing is due to Revel doing dynamic reflection and screwing up during this controller-scanning initialization. So now the question is: why is it having trouble scanning for controllers?
Your code appears to try to extend a controller in EventStream, which the Revel debug controller-discovery code will try to read as a Controller. However, the code as it stands is currently violating expectations of the framework by embedding a *GormController instead of a GormController; see the last part of the Controllers documentation.
I think the controller-discovery logic is simply choking because of this. Fix the EventStream structure definition.
If this does correct the issue for you, you should probably send a bug report to the Revel folks, because the error message you're getting back is pretty bad and non-local, because it doesn't mention the name of the thing it's trying to register as a controller when it fails.
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